Lighter eyes means lighter skin?

While trying to locate information on whether hair colour lightens skin tone, I found a few articles suggesting that eye colour does, blue eyes particularly. Here’s a couple of studies I’ve found. From what I’ve read, it seems that several recessive genes (red hair, blue eyes) lighten skin colour. It’s not totally clear if it’s just through geographical association with other genes though.

Ancestry informative markers (AIMs) are genetic loci showing alleles with large frequency differences between populations. AIMs can be used to estimate biogeographical ancestry at the level of the population, subgroup (e.g. cases and controls) and individual. Ancestry estimates at both the subgroup and individual level can be directly instructive regarding the genetics of the phenotypes that differ qualitatively or in frequency between populations. These estimates can provide a compelling foundation for the use of admixture mapping (AM) methods to identify the genes underlying these traits. We present details of a panel of 34 AIMs and demonstrate how such studies can proceed, by using skin pigmentation as a model phenotype. We have genotyped these markers in two population samples with primarily African ancestry, viz. African Americans from Washington D.C. and an African Caribbean sample from Britain, and in a sample of European Americans from Pennsylvania. In the two African population samples, we observed significant correlations between estimates of individual ancestry and skin pigmentation as measured by reflectometry (R2=0.21, P<0.0001 for the African-American sample and R2=0.16, P<0.0001 for the British African-Caribbean sample). These correlations confirm the validity of the ancestry estimates and also indicate the high level of population structure related to admixture, a level that characterizes these populations and that is detectable by using other tests to identify genetic structure. We have also applied two methods of admixture mapping to test for the effects of three candidate genes (TYR, OCA2, MC1R) on pigmentation. We show that TYR and OCA2 have measurable effects on skin pigmentation differences between the west African and west European parental populations. This work indicates that it is possible to estimate the individual ancestry of a person based on DNA analysis with a reasonable number of well-defined genetic markers. The implications and applications of ancestry estimates in biomedical research are discussed.

OCA2 controls eye colour, and TYR is a gene that harbours mutations for albinism. This seems to suggest that lighter eye colour could lead to lighter skin colour too. You see this in albino Africans, with partial albinism. They sometimes have blond hair and blue eyes, not the white hair and pink eyes of a full albino.

We have previously shown that a quantitative-trait locus linked to the OCA2region of 15q accounts for 74% of variation in human eye color. We conducted additional genotyping to clarify the role of the OCA2locus in the inheritance of eye color and other pigmentary traits associated with skin-cancer risk in white populations. Fifty-eight synonymous and nonsynonymous exonic single-nucleotide polymorphisms (SNPs) and tagging SNPs were typed in a collection of 3,839 adolescent twins, their siblings, and their parents. The highest association for blue/nonblue eye color was found with three OCA2SNPs: rs7495174 T/C, rs6497268 G/T, and rs11855019 T/C (P values of 1.02×10-61, 1.57×10-96, and 4.45×10-54, respectively) in intron 1. These three SNPs are in one major haplotype block, with TGT representing 78.4% of alleles. The TGT/TGT diplotype found in 62.2% of samples was the major genotype seen to modify eye color, with a frequency of 0.905 in blue or green compared with only 0.095 in brown eye color. This genotype was also at highest frequency in subjects with light brown hair and was more frequent in fair and medium skin types, consistent with the TGT haplotype acting as a recessive modifier of lighter pigmentary phenotypes. Homozygotes for rs11855019C/C were predominantly without freckles and had lower mole counts. The minor population impact of the nonsynonymous coding-region polymorphisms Arg305Trp and Arg419Gln associated with non-blue eyes and the tight linkage of the major TGT haplotype within the intron 1 of OCA2 with blue eye color and lighter hair and skin tones suggest that differences within the 5′ proximal regulatory control region of the OCA2 gene alter expression or messenger RNA–transcript levels and may be responsible for these associations.

Human pigmentation is a polygenic trait which may be shaped by different kinds of gene–gene interactions. Recent studies have revealed that interactive effects between HERC2 and OCA2 may be responsible for blue eye colour determination in humans. Here we performed a population association study, examining important polymorphisms within the HERC2 and OCA2 genes. Furthermore, pooling these results with genotyping data for MC1R, ASIP and SLC45A2 obtained for the same population sample we also analysed potential genetic interactions affecting variation in eye, hair and skin colour. Our results confirmed the association of HERC2 rs12913832 with eye colour and showed that this SNP is also significantly associated with skin and hair colouration. It is also concluded that OCA2 rs1800407 is independently associated with eye colour. Finally, using various approaches we were able to show that there is an interaction between MC1R and HERC2 in determination of skin and hair colour in the studied population sample.

Anyone interested in this might be interested in Razibs more in depth look at this here

This is my all time number one post on this blog, about ten percent of hits have come from this. Lord only knows why but about 150 people a day look at it. Why this one?

well, i lifted them from somewhere else🙂 it looks like the pigmentation genes have global effects. e.g., loss of function on MC1R is correlated with red hair, freckles and very fair skin, conditional on particular states at other genes. HERC2-OCA2 are the major locus of variation for eye color, but, they have some effect on *both* eye and skin color. SLC245 has a major effect on skin color, and some effect on the other pigmentation traits.

I read up on some MC1R variations for a ‘red headed caveman’ thing a while ago. I was wondering if being ginger was an prototype method of lightening skin to synthesise vitamin D before the Neolithic mutation for white skin appeared. Ginger hair with a basic darker skin colour wouldn’t cause so much burning, but would lighten it.

I was wondering if being ginger was an prototype method of lightening skin to synthesise vitamin D before the Neolithic mutation for white skin appeared.

there isn’t one method. there are several. that makes sense, light skin is usually just a loss of function, and there are a million ways to break biochemical pathways. OTOH, dark skin was probably a gain of function after we lost our fur, and there seems only one way to produce it.

though, i have to say that the MC1R varieties are very extreme, and seem to have major global effects. to some extent it is likely all these loci are polymorphic, but i’m under the impression that MC1R has the most extreme effects, so you might be right in that it’s a quick & dirty solution.

(note that over time one assumes that the same genes will be “hit,” but there are still different ways to break the same gene)

I can’t help wondering if the incidence of gingerness is descreasing since the SLC245 light skin became the standard in Northern Europe.
Ginger on top of a mid tone skin = olive skin and freckles.
Ginger + white skin = a world of sunburn, even in England.

First it may be relevant to repeat the biologers tumb-rule “genes don’t mutate, organisms do.” The genetic change is the reflection of a changed organism, that (may) copy itself during reproduction.

Besides cross-breeding that bring us back to the environment as cause for a variation of zyotic metamorposis and possible mutation.

Then it may appear as plain logic to assume that a change in environment – from the hot-spots of Kenya to the cold paleolithic areas of Caucasus or Iberia could cause the mutation from a black Bantu to a pale-faced Brit.

But that far from good enough to explain how some odd branch of the modern human could have mutated into the caucasian palefaces that seem to hower over most of this planet today.

Mendels simple laws of inherritance is still good enough to discuss the basics of this. Added a notion of Lamarck, of course – otherwiser it is problematic to explain any mutation consequent with the historic realities of the nature we actually live in – and are part of…

According to the principle of invective and receptive genes we have the old story about the brown-eyed man and the blue eyed woman, that got 4 children. Simplisticly speaking; According to the brown “dominance” three out of four children will be brown-eyed. Since this will repeat itself over and over we will end up with less and less pale, blue/green/grey-eyed and blondish people on the planet, rigth?

I think some etnologist have done some epidemolgy and spotted 2040 as the definitly last year for a complete blonde to be recreated on this planet. Most probably somewhere in Finland, accordingly, since they still have quite a few left – in a population with less than high mobility.
This obviously implies that – unless the blonds are restricted to reproduce only with blondes – they will soon be out of stock…!

So, – how could they occur at all, in the first place?! The genetic research seems to agree that we all have acommon origin – and the OoA-theory seem to explain where a how.
Which may seem so causal, since the primal human being obviously have been created in a tropic environment. The genetic markers seem to conirm that as well, since most the large populations live around the equator. Moreover they all have dark or dark-brown eyes, solid pigmentation and limited body-hair. The arctic species are obviously a later mutation, even thoigh they have spread some of their features around the sub-arctic and sub-tropic areas.
It is no big question that the “Tribe of Ursula” originated somewhere north of the
Mediterranean area. The question are stll many, though. For istance;

1)HOW could she occur – from a couple of post-African, fully brown-eyed parents?!

2) Since sun-burt is not a natural cause-effect of a gradual modiication, we need to ask what kind conditions and historical evolution that can possibly give such a result.

3) That leads straigth to the next question; How low levels of sunligth do we need to develop such an extreme mutation that rids itself of all the pigmentation it has, naturally?!

4) What climatic and other conditions are needed to make all male children grow extra body hair?

5) Thus Ursula would need a man with the exact same tendency of mutation.

6) Then their kids woud need to uphold this mutation and further evolve it – for a number of minimum 200 generations, or maybe 2000 generations – before the genetic spectre would have stabilized as firm basis for “Code Ursula” to reproduce as a new branch of the human specie – as in both sexes.

7) Since this new mutation would be very fragile for many generations, what would happen if a scout-club of the pre-agruculturists from the Levant called by to visit? And what if the “Alpine” descendants of tribe Ursula sent a few lads to get some new wives, ye know – down south?

8) If the Alpine caucasians now have grown to become 100 blonds, and two men and two women from their “ancient hometurfs” – such as the Levant – married into the tribe? That would allitterally kill the project since it would take them four kind each to produce six new brownies, that in turn would make 20 new brownies, then 60…

Given a relative constant population it wold take about 3-4 generations to make them all beutifully brown again…!

—

If the disappearing blondes did not exist,
whqat would be the probability for such a branch to develop, today?! Less than none, of course.

Still some of us keep brushing our corner- teeth as two bluegreen irises glance at my pale-grey morning-face – where only some brown and dark-brown freckles still reminds me of our ancient, orginal skin-color.

So – what happened to make it this extreme mutattin – and how could it pursue, endure and last until this caucasian kind had reproduced to populate all of the northern hemisphere – that layed bare and cold – after the end of ice-time?

According to the Canadian antropolgist peter Frost; “Human hair and eye colour are unusually diverse in northern and eastern Europe (and their) origin over a short span of evolutionary time indicates some kind of selection,” Frost adds that the high death rate among male hunters “increased the pressures of sexual selection on early European women, one possible outcome being an unusual complex of colour traits.”

“Hair and eye colour tend to be uniform in many parts of the world, but in Europe there is a welter of variants,” he said. “The mate choice explanation now being put forward is, in my mind, close to being correct.”

Frost’s theory is also backed up by a separate scientific analysis of north European genes carried out at Danish and Japanese universities, which has isolated the date of this genetic mutation to appear in the larger world at about 11,000 years ago.

The hair colour gene MC1R has at least seven variants in Europe and the continent has an unusually wide range of hair and eye shades. In the rest of the world, dark hair and eyes are overwhelmingly dominant.

Just how such variety emerged over such a short period of time in one part of the world has long been a mystery. According to the new research, if the changes had occurred by the usual processes of evolution, they would have taken about 850,000 years.(…)

Carlos Bustamante and his graduate student Kirk Lohmueller, wrote a paper earlier this spring arguing that deleterious mutations have reached high frequency in Europeans (moreso than Africans) because of a bottleneck during European history. The press reported this work as “Whites genetically weaker than blacks, study finds.” The hypothesis in the paper is that protein-coding sites otherwise conserved in most mammals may differ among humans because of relaxed selection in a bottleneck.

[…]
They propose that the European population was a small, isolated population of 5,700 effective individuals from 214,000 years ago up to the Last Glacial Maximum.

[..]– it implies no gene flow between Africans and Europeans across that entire span. You see, that is the only way that genetic drift can lead to this kind of result — large differences in frequencies between continents for hundreds of deleterious alleles. It takes a bottleneck of exceptional length, along with complete isolation.

Genetics can be very odd. Everyone with blue eyes tested so far (who isn’t an albino) has the same recent mutation which centers on Northern Europe. You have to remember Europeans have been in Africa for hundreds of years, there’s been some exchange there. Blue eyes aren’t good in bright African sunight, they let in too much UV and you can go blind young, so it gets selected out fairly quickly. Dark irises are a bit like built in sunglasses.

This article is more about a lightening effect, it’s a complicated interaction which is why you need to use large sample groups to get the average effect. But I do see your point; there’s a really cute picture of a little black boy with blue eyes here. It doesn’t seem to have much effect on him.

Certain melanin makes skin more vulnerable to sunburnDr. Brash had been curious why people with dark hair and fair skin weren’t as vulnerable to skin cancer as fair-skinned blondes or redheads[…]People with the other type of melanin—eumelanin—have darker hair. Interestingly, while dark-haired people with eumelanin can be fair-skinned, they don’t burn as readily as a blonde or a red-head.

The only advantage to “the type of melanin that
blondes and red-heads have—pheomelanin” is that it confers eye catching hair colours. Dark haired people can and do have very fair skin, without the disadvantage of more cancer.
The skin lightening for vitamin D theory is all wrong. The Pharmacology of Vitamin D the system of vitamin D metabolism in Figure 2 from the perspective of a system designed to control something, it becomes clear that this is a system better designed to cope with an abundance of supply, not a lack of it. The flow of vitamin D toward 25(OH)D is remarkably inefficient, with most bypassing it. Furthermore, there is no way to correct for deficiency of vitamin D, other than to redirect utilization of 25(OH)D toward 1,25(OH)2D production, which is the pathway most acutely important for life. […]the system of vitamin D metabolism is effectively a designed for adjusting for higher inputs, not lower inputs,

It could be explained that the metabolism of people in cold countries is still adapted to the high UVR environment where humans evolved, However, if true this ought to make the efficiency of the first step (synthesis in the skin) imperative for North Europeans in particular. They have to go 6 months without any synthesis of vitamin D in the UVB-less months.

Why have north Europeans not evolved any changes to their limit of UVB synthesized Vitamin D (20,000IU) according to Vitamin D PhysiologyOnce you make about 20,000 units, the same ultraviolet light that created cholecalciferol, begins to degrade it. The more you make, the more is destroyed. So a steady state is reached that prevents the skin from making too much cholecalciferol. This is why no one has ever been reported to develop vitamin D toxicity from the sun, though it is possible when taken orally Why have Europeans who have to go several months without any synthesis of vitamin D not got a vastly higher limit than other people. They also tan on exposed skin long before the end of summer which reduces their efficiency at synthesizing D.
If light skin was anything to do with maximizing vitamin D then why does this their skin start to destroy vitamin D , limiting it to about 20,oooIU, this takes a mere 20 minutes in the summer. Surely north Europeans ought to be storing this excess in their bodyfat to see them through the winter.Vitamin D can be stored of course :- The sun is the most potent source. When the sun’s ultraviolet rays hit the skin, the skin makes the vitamin, which is rapidly absorbed in the blood and can be stored for several months, mostly in the blood and fat tissue. This is why it’s hard to figure out how much supplemental vitamin D people might need This mechanism for the destruction of vitamin D would be the first thing to be altered by natural selection when early modern humans entered Europe. Light eyes are associated with light skin but they are both too late for vitamin D synthesis at high latitude to be the cause.SEXUAL SELECTION AND HUMAN GEOGRAPHIC VARIATION
points out “There are other problems with attributing these color traits to weak solar UV:
Ancestral Europeans whitened in skin color and diversified in eye color long after they
had entered Europe’s northern latitudes about 35,000 years ago (Table 1). Among
Europeans, the allelic changes at the SLC45A2 (AIM1) skin-color gene are dated to
~ 11,000 BP and those at the SLC24A5 skin-color gene to ~ 12,000–3,000 BP (Norton &
Hammer, 2007; Soejima et al., 2005). No less recent are the changes at other skin-color
loci and the OCA2 eye-color gene (Voight et al., 2006). At the OCA2-HERC2 gene
complex, the new eye-color alleles are believed to be very recent, possibly 10,000 to
6,000 years old (Eiberg et al., 2008). As a Science journalist commented: “the implication
is that our European ancestors were brown-skinned for tens of thousands of years”
(Gibbons, 2007). If the agent of selection were weak solar UV, why did it wait so long…

My youngest daughter–adopted, genetically my niece, and we know nothing at all about her father–had red hair, very fair skin, and brown eyes. She freckled quite a lot.

Many black people freckle. It’s just harder to see their freckles.

Many people who are 1/8 black and 7/8 white have bright red hair and emerald green eyes.

I am not up on genetic studies, so I can’t begin to guess the reasons for this. I simply state it for what it’s worth. I, BTW, am 93% white, 3 1/2 % Cherokee, and 3 1/2% black, tribe unknown. I have brown hair, blue eyes, fair skin (but not as fair as my daughter’s) and I freckle.

Black people also blush. You have to be a good observer to notice that, but when you’re teaching eighth grade in an all-black school you had better be a good observer, particularly if half your students are taller than you.

Frankly I don’t understand any of this discussion. Ancient Egypt didn’t seem to pay much attention to race. There were dynasties of black pharaohs, though not many, and interbreeding seems to have been taken as a matter of course. In the Bible, Miriam is furious at Moses for having an Ethiopian wife; having been raised in the royal court, he saw no reason whatsoever not to have an Ethiopian wife. (This is one of the places where our prejudices show up. We’re far more willing to say that the father-in-law of Moses had multiple names than to admit that Moses clearly had multiple fathers-in-law. I’m a Mormon, so I don’t care how many fathers-in-law Moses had.)

I know why people are looking at this post. It’s because they look over in your sidebar and see the top ten posts. They see this as the number one post, so they think, “It must be good if so many people are looking at it.” So they click on it, contributing to keeping it the number one post, just by virtue of its already being number one. Same thing happens on my blogs. I’m sure that’s why people are looking at what are my top posts.

Some comments from a nonspecialist in genetics:
– The pattern of light/mixed eye colour, very fair skin, and dark hair is very common in western Europe (Ireland to Central Europe). Sunburn and skin cancers are high-risk, but there seems to be some protection against rickets (at least).
– Elementaryteacher’s remarks are valid, but only part of the picture. Some proportion of the relevant population is choosing the site because it is their primary interest. What proportion? I have no idea.

Agree with Lorne Henwood, also from a nonspecialist – I have dark hair, very pale skin and green eyes, am part Welsh and part Irish and a lot of people where I grew up had the same sort of colouring (although blue eyes were more common).

However I also neither burn nor tan easily, so I’m not sure where that comes in, but that’s my genes!

Your site is so interesting. I love the genetic diversity of mankind and have always been interested in how it arose. I enjoy your photos of people from all over the world, especially those that go against our assumptions.

I have almost black hair and dark brown eyes, but very, very pale skin with freckles, that burns in five minutes in the sun. My family is half brown- and half blue-eyed, and the blue eyes do not coincide with the pale skin.

Always wondered how such pale, difficult skin evolved: sexual selection, rickets prevention, or was it just an accident? When I went to Ireland, there were a lot of people who looked pale with dark hair like me, but all with light eyes. (I am a very small part Algonquin Indian but I suspect that is where the eyes come from.)

All the above really interesting. I am auburn haired, blue/grey eyed and freckled, burn easy and don’t tan easy and B+ blood group, and taller than rest of family. My mother and father had raven black hair and blue eyes, and small. I’ve been told I have recessive genes….where does red hair roughly speaking come from? Does this link with Scandinavia at all?